Cytoplasmic parafibromin/hCdc73 targets and destabilizes p53 mRNA to control p53-mediated apoptosis.

The parafibromin/hCdc73 is a component of the PAFc, which controls RNA polymerase II-mediated general transcription. In parathyroid carcinoma and familial autosomal dominant hyperparathyroidism-jaw tumour (HPT-JT), hCdc73 mutations are heavily implicated, yet the underlying mechanism of its carcinogenic action is poorly understood. Here we demonstrate that hCdc73 specifically controls messenger RNA stability of p53 and p53-mediated apoptosis. hCdc73 is associated with mature p53 mRNA in the cytoplasm and facilitates its degradation. Cytoplasmic hCdc73 physically interacts with eEF1Bγ and hSki8, and this interaction is required to bind and destabilize p53 mRNA. Furthermore, enhanced association of p53 mRNA with a cancer-driven hCdc73(K34Q) mutant was also observed. As a result, reduced p53 expression as well as enhanced cell proliferation was acquired in the hCdc73 (K34Q)-overexpressed cells. Altogether, our findings indicate that hCdc73 directly targets p53 mRNA to repress p53 expression, and aberrant regulation of this interaction may lead to tumour progression.